High current inductive coupler and current transformer for power lines

Abstract

There is provided an inductive power line data coupler. The coupler includes (a) a magnetic core having a high magnetic permeability at a data communication frequency and being configured to allow a power line of a power distribution system to be routed through the magnetic core to serve as a primary winding, (b) a data signaling circuit that provides a secondary winding through the magnetic core for coupling a data signal between the power line and a communication device, and (c) a choke coil coupled to the data signaling circuit for creating a flux-canceling power frequency current opposite in direction and comparable in magnitude to a power frequency current. The coupler may also include a circuit for sensing a level of current in the power line.

Description

[0001] The present application is claiming priority of (a) U.S. Provisional Patent Application Serial No. 60 / 376,377, filed on Apr. 29, 2002, and (b) U.S. Provisional Patent Application Serial No. 60 / 416,603, filed on Oct. 7, 2002.[0002] 1. Field of the Invention[0003] The invention generally relates to power line communications, and more particularly, to avoiding magnetic saturation in a power line inductive coupler.[0004] 2. Description of the Related Art[0005] In a power line communication system, power frequency is typically in a range of 50-60 Hertz and a data communication signal frequency is typically in a range of 1-50 MHz. An inductive coupler for coupling modulated data onto and off of power lines includes a magnetic core through which pass the power line and a secondary winding. This is described, for example, in patent application Ser. No. 09 / 752,705, filed Dec. 28, 2000, patent application Ser. No. 10 / 082,063, filed Feb. 25, 2002, and provisional patent application No. ...

AI Technical Summary

Problems solved by technology

One limitation to the usage of such couplers on high current primary and secondary wires is the limited ability of the magnetic cores to withstand large magnetization currents without magnetic saturation.

Saturation degrades performance in two ways.

First, saturation reduces the magnetization inductance, which increases the shunt admittance loading on the data signal.

So if the modulation depth exceeds some particular value, this modulation causes data errors.

Increasing the number of turns is also impractical, because the coupler is usually installed on large diameter power lines without interrupting the power circuit.

Such saturation may limit the maximum power frequency current that may be induced in the secondary winding, and prevent its overheating.

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